Charge-coupled devices are broken down to two major categories depending upon the locations of the channel to be formed, including a category of surface-channel charge-coupled devices and a category of buried-channel charge-coupled devices. In terms of the driving scheme, on the other hand, there are charge-coupled devices of the single-phase, two-phase, three-phase and four-phase designs. A charge-coupled device of any of these types and designs is essentially a functional device constituted by a MOS structure providing a built-in scanning function and capabilities of storing information. Such a functional finds its typical applications in an image sensing array, an analog delay device, and a digital filter as well known in the art.
Known charge-coupled devices include a device having the capability of eliminating excess carriers for providing an effect to suppress the blooming which result from the carriers overflowing a pixel area included in the device. Charge-coupled devices having such anti-blooming capability include those which have vertical or horizontal overflow drain schemes and those which have surface regeneration schemes, both of which are well known in the art. Devices with the overflow drain schemes are however not fully acceptable for their anti-blooming capabilities which are susceptible to fabrication process variations which degrade the field of fabrication of the devices. Charge-coupled devices having the surface regeneration schemes are also not satisfactory because of their inadequate capabilities of suppressing the blooming phenomena although these devices can be fabricated with acceptable yields.
It is, accordingly, an important object of the present invention to provide a semiconductor charge-coupled device having a novel and saliently enhanced anti-blooming capability.
It is another important object of the present invention to provide a process of fabricating such an improved semiconductor charge-coupled device.